Since graduating from university, Speirs has played
Sloan in
Eragon, Andy Fellows in
Making Waves and with
Ricky Gervais in
Extras, as well as playing
Captain Tarpals in
Star Wars: Episode I – The Phantom Menace and having a small role in ''
Pirates of the Caribbean: Dead Man's Chest''. He appears in
Kröd Mändoon and the Flaming Sword of Fire, a comedy fantasy series in which he plays Loquasto, an oafish servant, "who belongs to a race of pig-like creatures known as Grobble". He wrote his first film,
Caught in the Act, in 2008 and starred in it as the lead character. Based on his memories of growing up in south Wales, it was filmed in the Merthyr Tydfil area. Speirs also appeared in the Gervais and
Stephen Merchant film
Cemetery Junction released in 2010, a part which was written particularly for him. Speirs also appeared as the bouncer at Mother McOakley's Tavern in
Burke and Hare, a
British black comedy directed by
John Landis and released (in the
United Kingdom) in October 2010. He also starred in a CBBC show called Sadie J where he portrayed Sadie's dad, a mechanic. Other roles which Speirs is known for include his portrayal of
Bernard Bresslaw in
Cor, Blimey!, Big Alan Williams in
Stella and Colour Sergeant Wormwood in ''
Sharpe's Peril''. He also appears as a postman on the last episode of
Miranda season 3. Speirs played depressed geography teacher and caretaker Mr Gareth Barber in the
BBC One sitcom
Big School for two series in 2013 and 2014. In 2013, Spiers played PC McClintock in the Christmas TV film
Gangsta Granny, an adaptation of the book written by
David Walliams. He played the role of Dad in the 2014 TV film
The Boy in the Dress, also written by Walliams. In 2015, he appeared in the TV spin off
The Bad Education Movie playing Don alongside the main cast of
Bad Education as well as many other guests in the movie. The same year, he also appeared in the pilot of the radio sitcom
Ankle Tag, which went on to air three series in 2017, 2018 and 2020. In 2016, he appeared in
Ben Elton's
BBC One comedy series
Upstart Crow playing
Richard Burbage, the actor and leader of Will's acting company. He has continued in this role for three series (2016, 2017 and 2018) with two Christmas spin-offs in 2017 and 2018 and in the London West End in Elton's stage version of the show titled
The Upstart Crow. He has created, written and starred in
The Tuckers for BBC Wales and BBC iPlayer. In 1998, he appeared in the video for the
Super Furry Animals song
Ice Hockey Hair. ==Personal life==